Damage Control

Feeling sore and achy after your last run? When to press on and when to back off.

It can make you limp down the stairs or struggle to get out of your chair. But that doesn't mean muscle soreness is all bad. "Muscles go through physical stress when we exercise, and the discomfort that stress causes may be perfectly normal," says Allan Goldfarb, Ph.D., a professor of exercise physiology at the University of North Carolina-Greensboro. In fact, muscle soreness is often a good thing. "It's proof your body is adapting and growing fitter," Goldfarb says. "You're reprogramming your muscle structure and making weaker cells stronger."

This can make your job as a responsible runner who wants to avoid injury tricky. If you park yourself on the couch after feeling any inkling of tenderness, your training could come to a standstill. But if you push through the pain, you might hurt yourself. So how do you toe the line between a healthy dose of creakiness and pain that's a sign of trouble?

ON THE RUNSometimes the physical stress of exercise manifests itself as soreness while you're still running. That's because the action of running pushes your body's weight downward—and even the most cushy shoes can't alone handle the shock. "Some of the force goes back into your muscles," Goldfarb says. "That shock-absorption process releases chemicals that can activate pain receptors."

You can minimize midrun soreness by making sure you are in good shoes that aren't too worn (replace them every 400 to 500 miles) and choosing softer running surfaces when possible. And consider doing the next day's easy run on the treadmill, which has more give to help your recovery. When soreness escalates beyond slight discomfort, back off the pace (take walk breaks) and distance (take a shortcut or stop running and walk the remaining miles). Follow up with at least one rest or cross-training day—don't try to make up for the missed mileage.

AFTERSHOCKYou may feel fine during and right after a workout, only to discover you're quite sore a day or two later. "The gradually increasing discomfort that peaks 24 to 48 hours after activity and disappears five to seven days later is called delayed onset muscle soreness (DOMS)," says Carol Torgan, Ph.D., an exercise physiologist in Bethesda, Maryland. DOMS usually occurs when the leg muscles have performed an eccentric contraction (which increases tension on a muscle as it lengthens). Speedwork, races, long runs, or any type of workout you're not used to are other causes. "Intense or new activities put a lot of stress on muscle cells," Goldfarb says. "Some of those cells are strong from your regular workouts, but when you work your body in a new way, you hit some cells that are weaker. The weaker ones develop microtears." This damage causes achiness. The good news is that once your muscles repair themselves and grow stronger, they are more resistant to damage for up to eight weeks.

While it's okay to do an easy run while you're dealing with DOMS, hold off on doing another intense workout for a few days. And expect to feel a little stiff during the first mile or so. It's important at this point to recognize the difference between a Wow, I really pushed myself and a worrisome Oww, I really hurt. "If the soreness lasts longer than a week, it develops into pain, or there is any sign of swelling or redness, see a doctor," Torgan says.

That said, running or racing your best does not necessarily mean hobbling for the ice pack afterward. "If you are perfectly trained for a race, you may not be sore afterward because you didn't stress your muscles in a new way to lead to damage," Torgan says. "If you think of times that you were really sore after a race, typically there's an element that you didn't properly train for, such as not enough hill work. Or you raced significantly faster than your training pace."

AGE LIMITAs our muscles become conditioned to certain activities, they are less likely to become sore. "Muscles that are stressed will rebuild and adapt and cause less discomfort over time," Torgan says. "Think of it as a survival mechanism." There is, unfortunately, an exception to this rule. As we age, we become more prone to pain. There are two reasons, according to Goldfarb. First, we lose muscle cells—typically because of inactivity, but also just because, shoot, that's part of the aging process. That means there are fewer cells to recruit during a workout. The ones that are engaged will work overtime to get you to the finish line, but they'll also suffer the repercussions: tears and inflammation. Aging also slows down the body's muscle-repair mechanisms. "The protective processes in muscles are down-regulated and our connective tissue doesn't work as well," Goldfarb says.

That's why even the most talented masters runners take extra rest days and spend more time cross-training than they did in their younger years. You can still work hard and perform well as you age—so long as you prioritize recovery.

What a Relief

Achy, sore, tender muscles? Six ways to ease the hurt

ICE BATH Sitting in a cold tub for 10 to 20 minutes after a hard run helps flush out waste products and reduce swelling and tissue breakdown, Allan Goldfarb, Ph.D., says. You can also apply an ice pack to individual sore spots.

ACTIVE RECOVERY Twenty to 30 minutes of low-impact exercise increases blood flow to muscles to reduce trauma and re-establish the body's pH level, Goldfarb says. Cross-training the day after an intense workout can help you recover from a race, speed session, or long run, Carol Torgan, Ph.D., says.

MASSAGE Researchers in Australia found that sports massage may help reduce muscle soreness by as much as 30 percent. "Massage may increase blood flow to the damaged muscles and enhance recovery," says lead study author Ken Nosaka, Ph.D.

GENTLE STRETCHING "Stretching loosens muscles while lengthening them, and this allows them to relax and get back full range of motion," Goldfarb says. Hold gentle stretches for about 30 seconds at a time, postrun.

NSAIDS Aspirin, ibuprofen (Advil and Motrin), and naproxen sodium (Aleve) alleviate muscle soreness by preventing the body from making prostaglandins, substances that control pain and inflammation. "The problem is that NSAIDs slow the repair process by disrupting the re-synthesis of proteins, so use them sparingly," Goldfarb says.